In a continuing study of the reaction of the steroid side chain with phosgene, it has been found that 17 alpha-hydroxy-20-ketones bearing either ethyl or acetoxy methylene groups at C-21 afford stable 20-chloro-17,20-cyclic carbonates in good yield when treated with phosgene in a mixture of pyridine and methylene chloride. Unlike 20- chloro-20,21-cyclic carbonates, these products are very resistant to dehydrohalogenation in hot pyridine or aceton-sodium iodide- triethylamine. Preliminary experiments have shown, however, that under other reaction conditions C-20-substituted-17,20-cyclic carbonates are formed. It is our intention to study in detail the properties and reactions of these new cyclic chlorocarbonates. Other projects, now in progress or soon to be initiated, may be listed as follows: The preparation of the 18- and 19-hydroxycholesterols from 11 beta-hydroxycholesterol acetate, employing the Barton photolysis method, will be attempted. We have been unable to introduce a hydroxyl group at C-20-deoxysteroids by microbiological means, but it has been observed that the extent of hydroxylation at C-6 is greatly influenced by the presence or absence of oxygen functions at the C-17, C-20, and C-21 sites. At present these studies employ a common mold as the enzyme source but shortly will be extended to higher plant and mammalian tissue systems. A number of steroid side chain aldehydes have been prepared, and we intend now to study the influence of structure on their reduction by liver alcohol dehydrogenase.